Multiple stage reforming process



V. HAENSEL ET AL MULTIPLE STAGE?` REFORMING PROCESS Oct. 23, 1955 FiledFeb. 23, 1952 BOLVNOILOVHS' HOLOVSH HOLOVB U Ill.

nited States Patent MULTIPLE STAGE REFORMING PROCESS Vladimir Haenseland Henry W. Grote, Hinsdale, Ill., assignors to Universal Oil ProductsCompany, Chicago, Ill., a corporation of Delaware Application February23, 1952, Serial No. 273,102 Claims. (Cl. 196-50) This invention relatesto a method for reforming gasoline fractions to provide both motor fueland aviation gasoline. More specifically, the improved operationprovides a multiple step integrated and combined process for convertingoletinic gasolines, or alternatively, converting both cracked andstraight-run `gasolines to high octane fuels.

Where cracked gasolines, or other olenic naphthas and gasolines, are tobe reformed, it is desirable to subject the stream to saturation byhydrogenation prior to carrying out the reforming step. In the catalyticreforming operation, there is normally some hydrocracking andisomerization of parans, as well as the dehydrogenation of naphthenes,in order to effect the overall increase in octane number. It is aprincipal feature of a part of the present improved process to effectthe reforming in the presence of an improved substantiallynon-regenerative catalyst comprising platinum-alumina and combinedhalogen. As a rst step of the present process, a catalytically orthermally cracked gasoline fraction, together with hydrogen,fis passedinto contact with a suitable hydrogenation catalyst prior to enteringthe reforming zone. The hydrogenation catalyst is preferably cornposedof platinum and alumina, either with or without combined halogen,however, a cob,alt-'molybdenumalumina catalyst or other sulfur resistantcatalyst may be used Vto advantage.

In the reforming step, in orderto obtain a high degree of thearomatization of the naphthenic components in the naphtha or gasolinestream, the saturated stream is also preferably subjected todehydrogenation inthe presence of an improved platinum-alumina-combinedhalogen catalyst. This catalyst is a recently developed reformingcatalyst of superior quality providing superior conversion results underlong periods of use, being substantially non-regenerative when usedunder proper conditions. Where a straight-run gasoline fractionis to bereformed along with the olefinic fraction, the former may be introduceddirectly into the dehydrogenation zone in admixture with thehydrogenated stream.

Also, as a part of the present improved combined operation, after thedehydrogenation, the resulting aromatics are separated from thenon-aromatic portion of the product stream. These non-aromatics aresubjected to. hydrocracking in" the presence of a suitable hydrocrackingcatalyst and hydrogen which is obtained from the dehydrogenation stage,with the conversion effected at a higher pressure than that maintainedin the aromatization step. A platinum-aiumina-combined halogen catalystmay be used advantageously in this hydrocracking'step, however, it isnot intended to limit the present improved combined operation to thatmaterial alone. For example, a hydrogenation and cracking catalyst suchas a silica-aluminanickel composite may be used to advantage in thehydrocracking step.

It is a principal feature of the present invention to provide adesirable multiple step combined reforming operation whereby theresulting productstreams Vare suitable for both high octane motor andlaviation fuels'.

' velocity in this step may also be in the range of 2,768,12 vifatentedOct. 23, 1956 into contact with a sulfur resistant hydrogenationcatalyst and effecting the saturation thereof, contacting the resultinghydrogenated fraction with hydrogen and a platinum-alumina catalyst atreforming conditions effecting the dehydrogenation and aromatizationthereof, cooling and separating the resulting product stream to providea liquid stream and gaseous hydrogen containing stream, separatingaromatic hydrocarbons and non-aromatic hydrocarbons from the liquidstream, passing the nonaromatic hydrocarbons together with hydrogen intocontact with a hydrocracking catalyst at conditions effecting thehydrocracking thereof, cooling the resulting hydrocracked product streamand separating it to provide a liquid stream and a gaseous hydrogencontaining stream, recycling the latter into contact with the olenichydrocarbon fraction as the hydrogen stream being mixed therewith, andfractionating the resulting hydrocracked liquid boiling stream toprovide a high boiling fraction suitable for motor fuel and a lowboiling fraction suitable for aviation fuel.

In a preferred embodiment of the present combined operation,substantially different operating conditions are utilized in the variouscontacting zones in a manner providing optimum conversion conditions.Thus, in the rst stage of contact where the catalytically crackedfraction or olefinic fraction is saturated, conditions favoringhydrogenation are utilized, with temperatures within the range of fromabout 550 F. to about 850 F., while at a pressure of greater than p. s.i. g., say in the range of from about 100 to 800 p. s. i. g. The spacevelocity (which is defined as the weight of hydrocarbon charge per hourper weight of catalyst in the reaction zone) may be relatively high, sayin the range of from about l to 50, and the hydrogen to hydrocarbon moleratio in the range of from about l to 10.

The dehydrogenation stage is favored at high temperatures, say of theorder of from about 600 F. to about 1000 F., and lower pressures, say inthe range of from about 50 to 600 p. s. i. g. and preferably less thanabout 500 p. s. i. g. The space velocity through the dehydrogenationzone may also be relatively high, say Within the range of from about 0.5to 30, while the hydrogen to hydrocarbon ratio may also be of the orderof from about l to l0.

The hydrocracking step, for the non-aromatic fraction, is favored at aslightly lower temperature than that in the dehydrogenation Zone, say ofthe order of from about 550 F. to 750 F., and at high pressure, saywithin the range of from 500 p. s. i. g. to 2000 p. s. i. g. The spacefrom about 0.5 to 30, while the hydrogen to hydrocarbon molal ratio maybe in the range of from about l to l5 and preferably above about 4.0.

The platinum-alumnia-combined halogen catalyst, which is preferred foruse in our combined reforming processes may contain substantial amountsof platinum, but for economic as Well as yield and quality reasons, theplatinum content usually will be within the range of from about 0.05% toabout l1.5%. The concentration of halogen ion in the reforming andhydrocracking catalyst may be within the range of from about 0.1% toabout 8% by weight of the alumina on a dry basis. However, the fluorideion appears to be more active than the chloride ion and therefore willbe used within the range of from about 0.1% to about 3% by weight of thealumina on a dry basis. The chloride ion may be used within the range offrom about 0.2% to about 8% by weight of the alumina on a dry basis. Ofcourse, both fluoride and chloride ions may be used together to providethe halogen containing catalyst. Bromide and iodide ions may be used,but have been found to provide a lesser activity and preferably theaforementioned fluoride and chloride ions are combined with theplatinium-alumina catalysts.

Reference to the accompanying diagrammatic drawing and descriptionthereof will aid in more clearly setting forth the combined andintegrated steps of the present invention for producing premium fuelsfor both aviation and automobile use.

Referring now to the drawing, there is shown a cracked gasoline fractionhaving a 200-400 F. end point, passing by way of line 1 and valve 2through a suitable heater 3 in admixture with a hydrogen stream,obtained as will be set forth hereinafter and entering from line 4. Thecombined gasoline stream and hydrogen is heated to a temperature withinthe range of from about 550 F. to about 850 F., and in a specificembodiment say to about 700 F. This heated hydrocarbon and hydrogenstream passes through line 5 at a pressure of say about 600 p. s. i. g.into a hydrogenation reactor 6 and into contact with a suitable sulfurresistant catalyst, which in a desirable substantially non-regenerativeoperation may be the platinum-alumina-combined halogen catalyst asdescribed hereinbefore, or alternatively a platinum-aluminacatalystwithout halogen combined therewith. In the reactor 6, the olefins areconverted to provide corresponding saturated parafns and thecyclo-olefins are converted to provide corresponding naphthenes. Theresulting fraction passes from reactor 6 by way of line 7 and valve 8into a heater 9 prior to entering the dehydrogenation zone. Actually thehydrogenation step is exothermic so that the saturated stream passed toheater 9 may rcquire but a very small amount of additional heating.

In the particular embodiment shown, a straight-run gasoline fraction,which is preferably debutanized, is combined with the hydrogenatedfraction, and is introduced into line 7 by way of line 10 and controlvalve 11. The combined streams are heated within the furnace 9 to atemperature within the range of from about 750 F. to about 1000 F., andmore particularly in this embodiment, to about 900 F. prior to beingintroduced into the first dehydrogenation reactor 12, by way of line 13.The hydrocarbon stream preferably contacts the improvedplatinum-alumina-combined halogen catalyst in reactor 12 at a pressureless than 500 p. s. i. g., say at about 300 p. s. i. g. in order toprovide optimum aromatization conditions.

Excess hydrogen is utilized in combination with the stream passingthrough hydrogenation reactor 6, in order to readily provide forsaturation of the stream and so that hydrogen is present to mix with thehydrocarbon stream entering reactor 12, providing a hydrogen tohydrocarbon charge ratio, which is in the range of from about 1 to 10and preferably at least about 4. The partially aromatized anddehydrogenated stream leaving reactor 12 by way of line 14 and valve 15enters intermediate heater 16 so that the temperature of the resultinghydrocarbon and hydrogen stream may be again raised to the order ofabout 900 F. prior to entering a reactor 17 by way of line 18. Thedehydrogenation reaction is endothermic and in order to obtain anefficient conversion with a high production of aromatics it isadvantageous to maintain a relatively high temperature. It is of coursenot intended to limit the use of the present invention to any set numberof dehydrogenation reactors and accompanying intermediate heaters.Therefore, while two reactors are indicated, it is to be understood thatthree or more may be incorporated in the unit.

A resulting reformed stream, with substantially all of the naphthenesamortized, and with hydrogen formed in the reactors 12 and 17, leavesreactor 17 by way of line 19 and valve 20 to become cooled in a suitableheat exchanger or cooling means 21 and pass from the latter by way ofline 22 into a separating zone 23. In the separating zone 23, a gaseoushydrogen containing stream is withdrawn from the upper portion thereofby way of line 24 and valve 25, while a liquid dehydrogenated stream iswithdrawn from the lower portion of the separator by way of line 26 andvalve 27. In accordance with the combined operation of the presentprocess, the liquid stream from line 26 is passed into a fractionatingzone 28 to effect the debutanization thereof. The resulting gaseousfraction, containing butane and lighter components, is discharged fromthe upper portion of the fractionator 28 by way of line 29 and valve 30,and may be used as a gaseous fuel. The debutanized liquid fraction iswithdrawn from the lower portion fractionator 28 by way of line 31 andvalve 32 and passed to a suitable aromatic extraction unit indicated at33. The latter is indicated diagrammatically and may comprise a solventextraction system, or other suitable separating means to provide thesubstantially complete separation or extraction of the aromaticcomponents. The aromatic components withdrawn from unit 33 by way ofline 34 and valve 35 may be in turn fractionated to provide benzene,toluene, and Xylene. The materials may then be used for aviation fuelblending, or for any other purpose. The nonaromatic components fromextraction unit 33 are withdrawn by way of line 36, valve 37, and pump44 and then passed through heater 38 and line 39, having valve 40, to ahydrocracking zone 41.

In accordance with a specic operation of the present invention, hydrogenseparated and passed from the dehydrogenation step by way of separator23 and line 24 is raised to a high pressure in a suitable compressor orpumping means 42 and passed by way of line 43 into admixture with thenon-aromatic stream entering heater 38 by way of line 36. This combinedstream is heated lto a temperature as hereinbefore noted, of the orderof about 550 F. to 750 F. and preferably say at about 650 F., while at apressure above 500 p. s. i. g., as hereinbefore noted, and morespecifically say at about 800 p. s. i. g., prior to entering thehydrocracking reactor 41.

. The catalyst maintained within reactor zone 41 may be aplatinum-alumina-combined halogen catalyst, as previously noted, or asuitable combined hydrogenation and cracking catalyst effecting theselective cracking and branching of this substantially paranichydrocarbon stream to provide lower molecular weight and higher octanefractions. Also, as previously noted hereinbefore, it is not intended tolimit the catalyst to any one material in this particular zone. Theresulting hydrocracked fraction from zone 41, together with excesshydrogen, is passed by way of line 45 and valve 46 through cooling means47 and line 48 to a separator 49. From separator 49, a resultinghydrogen containing gaseous stream is withdrawn by way of line 4 andvalve 50, while a resulting hydrocracked liquid fraction is withdrawn byway of line 51 and valve 52. A portion of the hydrogen containing streamor from separator 49 may be vented by way of line 53 and valve 54 toprevent the build up of methane or other light gases, however, thelarger portion of the stream is recycled to the hydrogenation zone tocombine with the cracked gasoline stream entering line 1 as hereinbeforeset forth. It is also to be noted that the separator 49 is maintained ata substantially high pressure, say of about 700 p. s. i. g., permittingthe discharge of the hydrogen stream into the hydrogenation zone andsubsequently into the dehydrogenation zones at lower pressures than thatmaintained within the hydrocracking step. In other words, the hydrogenstream utilized in. the hydrocrackiiig zone 41` at' about 800 pf S-ismay., hsztdacsd'fa @worden gf about 600 p. s. i. g. atthehydrogenation reactor 6, and toa still lower' pi'es url e at the'dehydrogenation reactors. The use of arshingle circulatory systemforlithe hydrogen stream permits` the use of but a single compressor421e maintainontinuous movement of the hydrogen through all of thecontacting zones. The hydrocracking zone being the highest pressure zonereceives the high pressure hydrogen stream resulting from thedehydrogenation zone, and the hydrogen then passes through substantiallylower pressure zones, specifically the hydrogenation zone 6 and thedehydrogenation zones 12 and 17 back tothe separator The hydrocrackednon-aromatic fraction leaving separator 49 by way of line 51 and valve52 is passed to a ractionator 55 and therein is debutanized to providean overhead gaseous fuel stream, of butane and lighter gases that isdischarged by way of line 56 and valve 57. A bottoms liquid fractionpasses by way of line 58 and valve 59 to another fractionator 60 inorder to effect another separation providing an overhead cut of highoctane fuel containing C hydrocarbons and fractions boiling to about 185F. This overhead fraction is indicated as being withdrawn by way of line61 and valve 62 to provide an aviation fuel, or blending component foraviation fuel. The bottoms fraction is indicated as a 185 F. to 400 F.boiling point cut, withdrawn by way of line 63 and valve 64, and thisfraction is particularly suitable as a high octane motor fuel. It is tobe noted that the .high degree of branching of the lower boiling parainconstituents produced during the hydrocracking step 41 provide the C5 to185 F. aviation fuel, that is particularly desirable from the standpointof lean mixture response. Thus, this overhead fraction from line 61 maybe blended with portions of the aromatic components, obtained from line34, to provide a desirable aviation fuel having both good lean and richmixture response characteristics.

The foregoing describes a particular embodiment of an improved combinedprocess for reforming and increasing the octane number of both crackedand straight run gasoline fractions. However, it is to be noted that, asmentioned in connection with the dehydrogenation step, one or morereactors or contacting steps may be utilized in connection with both thehydrogenation contacting and the hydrocracking contacting, and thatwhere two or more such catalysts contacts are made, suitableintermediate heaters or heating means may be incorporated to maintaindesirable temperature conditions. Further, the foregoing indicates thata catalytically or thermally cracked stream, is passed through the firststage of the operation, namely the hydrogenation step, whilestraight-run gasolines enter directly into the second stage of contact,however, natural gasolines and other uncracked fractions boiling Withinthe gasoline range and containing little or no oleiins may be alsopassed directly into the dehydrogenation zone.

We claim as our invention:

1. A method for reforming straight run and cracked gasoline fractions toprovide high octane number fuels, which comprises, passing said crackedfraction in the presence of hydrogen into Contact with a sulfurresistant hydrogenation catalyst and effecting the saturation thereof,combining the resulting saturated fraction with the straight rungasoline fraction and passing the mixture in the presence of hydrogeninto contact with ya platinumalumina catalyst under reforming conditionsand effecting the dehydrogenation and aromatization thereof, cooling andseparating the .resulting product stream to provide -a liquid stream anda gaseous hydrogen containing stream,

separating the resulting liquid stream into-aromatic hydrocarbons andnon-aromatic hydrocarbons and recovering the former, passing theseparated non-aromatic hydrocarbons with at least a portion of saidgaseous hydrogen containing stream into contact with a hydrocrackingcata- 6 lystl at hydrocracking conditions effecting hydrocrackingthereof, cooling'the resulting hydrocracked product stream andseparating it to provide a liquid stream anda gaseous hydrogencontaining stream, recycling -at least a portion of the latter streaminto contact with the cracked hydrocarbon fraction contacting saidhydrogenation catalyst, and fractionating the resulting hydrocrackedliquid stream to provide a high boiling fraction suitable for motor fueland a low. boiling fraction suitable for aviation fuel.

2. A method for reforming straight run and cracked gasoline fractions toprovide high octane number fuels, which comprises, passing said crackedfraction together with excess hydrogen obtained as hereinafter set forthat a pressure of the order of about 600 p. s. i. g. into contact with aplatinum-alumina-combined halogen catalyst and effecting thehydrogenation and saturation of said fraction, combining the resultingsaturated fraction with straight rnn gasoline and passing the mixturetogether with excess hydrogen from said hydrogenation contact at apressure of less than 500 p. s. i. g. into contact with a catalystcontaining platinum-alumina at reforming conditions and effecting thedehydrogenation and aromatization of said combined streams, cooling andseparating the resulting dehydrogenated product stream to provide agaseous hydrogen containing stream and a liquid stream, separating theresulting liquid stream into aromatic hydrocarbons and non-aromatichydrocarbons and recovering the former, passing the separatednon-aromatic hydrocarbons together with at least a portion of saidseparated gaseous hydrogen containing stream at a pressure greater than700 p. s. i. g. into Contact with a platinum-alumina combined halogencatalyst and effecting the hydrocraeking of said non-aromatic fractions,cooling the resulting hydrocracked product stream and separating it toprovide a liquid stream and a gaseous hydrogen containing stream,recycling at least a portion of the latter into contact with saidcracked hydrocarbon charge fraction as the aforesaid hydrogen mixedtherewith, and fractionating the resulting hydrocracked liquid stream toprovide a low boiling fraction suitable for aviation fuel and a higherboiling fraction suitable for motor fuel.

3. The method of claim 2 further characterized in that said hydrocrackedliquid product stream is fractionated and has butanes and lightermaterials separated therefrom in a first fractionating step, and theresulting debutanized fraction is separated in a second fractionationstep to provide a low boiling fraction containing C5 to about 185 F.boiling point material providing a desirable aviation fuel, and a higherboiling fraction containing F. to about 400 F. boiling point materialsuitable for motor fuel.

4. The method of claim 2 further characterized in that said crackedfraction undergoing saturation in the presence of saidplatinuin-alumina-combined halogen catalyst is introduced into contacttherewith at a temperature of the order of about 700 F., the resultingsaturated cracked fraction and the straight run fraction contacts saidplatinum-alumina catalyst at a temperature of the order of about 900 F.for effecting said aromatization step, and said non-aromatic fractioncontacting said platinum-alumina-combincd halogen catalyst is heated toa temperature of the order of about 650 F. for effecting thehydrocracking thereof.

5. A method for reforming an olefinic hydrocarbon fraction boiling inthe gasoline range which comprises catalytically hydrogenating saidfraction in the presence of excess hydrogen in a first zone, subjectingthe hydrogenated fraction to catalytic dehydrogenation and aromatizationin admixture with the excess hydrogen in a second zone, introducing astraight run gasoline fraction to said second zone for conversiontherein in admixture with said hydrogenated fraction, separating fromthe resultant products a hydrogen-containing gas, aromatic hydrocarbonsand non-aromatic hydrocarbons, re-

covering the aromatic hydrocarbons, Supplying theV separatednon-aromatic hydrocarbons to a third zone maintained under higherpressure than said rst and second zones, increasing the pressure on saidhydrogen-containing gas and introducing the same to the third zone,cataw lytically hydrocracking the non-aromatic hydrocarbons in saidthird zone, separating the normally liquid hydrocracked products fromhydrogen-containing gas, and supplying at least a portion of thelast-mentioned gas to said rst zone.

References Cited in the le of ,this patent v UNITED STATESYPATENTS l'

1. A METHOD FOR REFORMING STRAIGHT RUN AND CRACKED GASOLINE FRACTIONS TOPROVIDE HIGH OCTANE NUMBER FUELS, WHICH COMPRISES, PASSING SAID CRACKEDFRACTION IN THE PRESENCE OF HYDROGEN INTO CONTACT WITH A SULFURRESISTANT HYDROGENATION CATALYST AND EFFECTING THE SATURATION THEREOF,COMBINING THE RESULTING SATURATED FRACTION WITH THE STRAIGHT RUNGASOLINE FRACTION AND PASSING THE MIXTURE IN THE PRESENCE OF HYDROGENINTO CONTACT WITH A PLATINUMALUMINA CATALYST UNDER REFORMING CONDITIONSAND EFFECTING THE DEHYDROGENATION AND AROMATIZATION THEROF, COOLING ANDSEPARATING THE RESULTING PRODUCT STREAM TO PROVIDE A LIQUID STREAM AND AGASEOUS HYDROGEN CONTAINING STREAM SEPARATING THE RESULTING LIQUIDSTREAM INTO AROMATIC HYDROCARBONS AND NON-AROMATIC HYDROCARBONS ANDRECOVERING THE FORMER, PASSING THE SEPARATED NON-AROMATIC HYDROCARBONSWITH AT LEAST A PORTION OF SAID GASEOUS HYDROGEN CONTAINING STREAM INTOCONTACT WITH A HYDROCRACKING CATALYST AT HYDROCRACKING CONDITIONSEFFECTING HYDROCRACKING THEREOF, COOLING THE RESULTING HYDROCRACKEDPRODUCT STREAM AND SEPARATING IT TO PROVIDE A LIQUID STREAM AND AGASEOUS HYDROGEN CONTAINING STREAM, RECYCLING AT LEAST A PORTION OF THELATTER STREAM INTO CONTACT WITH THE CRACKED HYDROCARBON FRACTIONCONTACTING SAID HYDROGENATION CATALYST, AND FRACTIONATING THE RESULTINGHYDROCRACKED LIQUID STREAM TO PROVIDE A HIGH BOILING FRACTION SUITABLEFOR MOTOR FUEL AND A LOW BOILING FRACTION SUITABLE FOR AVIATION FUEL.